**So I tried making this with a crust, but the crust ended up sucking, and I realized that you don't even really need one, because the bars hold together all on their own. if you choose not to use one, I would suggest probably lining the pan with parchment or wax paper so you can pull the whole thing out of the pan, otherwise everything might just stick right too it.
1. In a medium or large bowl over a pot of simmering water, melt 1-1/2 cups white chocolate, peanut butter, and margarine. Remove from heat.
2. Mix in the coconut and marshmallows. Quickly and gently mix in the dark chocolate chips and transfer the mixture into the pan with or without a crust and spread evenly. (If you mix this up real good it will all become brown, and I like the way it looks better when it is more peanut buttery with a few chocolate swirls rather than straight up chocolatey.)
3. Put in the fridge to set for about an hour.
4. In separate bowls, melt the extra 1/4 cup of white and 1/4 cup dark chocolate. Put melted white chocolate into a piping bag with your smallest tip. Pipe zig zags of white chocolate from one corner of the pan to the other, and then from the other corner to the other corner. Repeat with the dark chocolate, going in between the lines of white chocolate. (You may also use a plastic baggie with the tip cut off, although a piping bag is reusable.)
5. Put in the fridge to set for about 15 minutes. Let the pan sit out of the fridge for a few minutes before you cut it into how ever many squares you desire.
Source of recipe: I modified this recipe from an assortment of non-vegan marshmallow square recipes.